^^^^ that is correct and always remember about that bypass valve. I have one in now ---- engine with 38 hours only and it has piston / cylinder noise back port area. My guess wrong by pass valve, maybe wrong cam that created water reversion - just guessing --- winter project so far have not looked at a thing other than start it up / idle warm up - located noise and parked it. Owner states its a new crate longblock . Jeez

a 572 you have your eyes on right now?

The guy in the Scarab section has the 572. Says all the clearances and cam were fine. I think all he had to change were valves and springs. Pretty sure he changed intake and carb, but by choice, not because it needed it. I would however bet a drink that the 572s in the OSO boat met a nasty end shortly after being installed.

My scarab boat was a 1994 model, and the GM Performance catalogue I had from that time frame definitely did state that the 502 ZZ motor was for auto and marine use.
After so many failures during the following years, maybe GM removed the marine portion.
Going back 15 years would take us back to 2001. Time does fly by.

"My scarab boat was a 1994 model, and the GM Performance catalogue I had from that time frame definitely did state that the 502 ZZ motor was for auto and marine use. "
IF you had a 19' Hondo/Sanger/etc. flatbottom V-drive I think the 502 ZZ could be considered a good choice for "marine application" Just saying.

I used a 502/502 short block assembly for my 208 Baja build. It comes with brass freeze plugs, so with the oil bypass change there is nothing else needed for it to be " marinized" other than the 502/502 cam lobe centers are not ideal for a boat (reversion prone). I used an UltraDyne roller cam, Edelbrock O port heads, Eddie Marine exhaust manifolds and could turn 5900 rpm on a 24 bravo prop. 12 years later it was still running perfectly when I sold it. I think the 502 short block is an ideal starting point, at least in my experience.

Last one i had outlived the boat. Aluminum large ovals i believe. ,and the street grind yet lumpy cam..i got it with the 6 qt pan but a huge aftermarket cooler and correct oil cooler bypass provision. and closed cooling.
Mine was a gen 6 block . When the transom went out it became a organ doner. Had buyers lined up for that trailer.lived a long horrible glorious life and is now in a 69 chevelle going strong . Still running the orig gmpp performer style intake i believe.

Aluminum water pump too . Btw.

I have the exact same setup and hopefully will have the same luck. I have CMI headers dry to the tip, and when I pulled the heads we didn't see much if any evidence of reversion even with the 110lsa. I may still swap that cam for a piece of mind though.

How long have you been running your 502 and with 110 LSA cam and of course running totally dry to the tip surely helps to

What heads and valve train set up ? Just asking